From: Mattias Engdegård <mattiase@acm.org>
Date: Sat, 25 Mar 2023 14:38:00 +0000 (+0100)
Subject: Generalise a LAP optimisation rule
X-Git-Url: http://git.eshelyaron.com/gitweb/?a=commitdiff_plain;h=52b67740d10df8ca539fdc2c7d50283997683141;p=emacs.git

Generalise a LAP optimisation rule

* lisp/emacs-lisp/byte-opt.el (byte-optimize-lapcode):
Accept (stack-set 1) as equivalent to (discardN-preserve-tos 1) in a
rule previously overlooked.  This is usually beneficial in code size
and almost always shortens dynamic paths.
---

diff --git a/lisp/emacs-lisp/byte-opt.el b/lisp/emacs-lisp/byte-opt.el
index 3c7aeb89525..0891ec80beb 100644
--- a/lisp/emacs-lisp/byte-opt.el
+++ b/lisp/emacs-lisp/byte-opt.el
@@ -2765,7 +2765,9 @@ If FOR-EFFECT is non-nil, the return value is assumed to be of no importance."
                       (or (memq (caar tmp) '(byte-discard byte-discardN))
                           ;; Make sure we don't hoist a discardN-preserve-tos
                           ;; that really should be merged or deleted instead.
-                          (and (eq (caar tmp) 'byte-discardN-preserve-tos)
+                          (and (or (eq (caar tmp) 'byte-discardN-preserve-tos)
+                                   (and (eq (caar tmp) 'byte-stack-set)
+                                        (eql (cdar tmp) 1)))
                                (let ((next (cadr tmp)))
                                  (not (or (memq (car next)
                                                 '(byte-discardN-preserve-tos